Using datatoc.c to make the splash screen blender 2.79
While this is still considered off-topic -

You are mixing up two similar names, you want to use datatoc but you are running ctodata.py. The page you read is out of date.

datatoc is a c program built as part of building blender. You can find it's source files in source/blender/datatoc/. When you build blender it will be in the build/bin folder.

Tou make use of a custom splash screen you need to build your own copy of blender, therefore the easiest way is to save your image as release/datafiles/splash.png and let the build process merge it into your blender.